Horsepower (hp)

• Definition: A unit of power measuring the rate at which work is done. One mechanical horsepower is roughly equal to 746 watts.
• History: Coined by engineer James Watt in 1782 to market his improved steam engines. He calculated how much power a brewery horse could continuously output to give customers a clear comparison.
• Common Uses: Rating the strength of automotive engines, electric motors, and heavy machinery.

Kilowatt (kW)

• Definition: A metric unit of power equal to one thousand watts, 1 kW = 1,000 W, where one watt is one joule of energy per second.
• History: The base unit (watt) was named in honor of James Watt in 1882 by the British Association for the Advancement of Science to create a cohesive universal metric power standard.
• Common Uses: Household electricity billing accounts (kilowatt-hours), measuring solar panel generation output, and rating electric vehicle motor performance.